At the input station of an endless belt conveyor used for transporting coal, ores, sand or gravel, or other granular material, spillage of material over the edges of the belt can frequently present a substantial problem. The spillage is usually controlled by positioning skirtboards along the edges of the conveyor belt for some distance downstream of the input location. Because the edges of rigid skirtboards engaging the belt edges could create undue friction and cause excessive wear on the belt, as well as undue loading of the conveyor drive, it has been conventional practice to position each skirtboard a short distance above the edges of the belt and to mount a flexible apron on the skirtboard to close the resulting gap. Some prior art systems have provided for vertical adjustment of the aprons to compensate for wear on their lower edges; skirtboards equipped with vertically adjustable aprons of rubber, canvas, or other resilient material are described in Roberts U.S. Pat. No. 2,593,610 issued Apr. 22, 1952 and in Clegg U.S. Pat. No. 3,499,523 issued Mar. 10, 1970.
While these previously known skirtboard and apron arrangements can provide effective control of spillage at the input station of the conveyor, some difficult problems remain. Thus, when continued wear on the lower edge of the apron requires a downward adjustment, the previously known systems have required that the conveyor be shut down. Such a shutdown is highly undesirable, particularly in a high volume conveyor system. Another difficulty with conventional skirtboard apron arrangements is encountered when wear on the apron reaches a stage such that apron replacement becomes necessary. Known systems have usually used a substantial number of bolts or similar fasteners that must be released before the apron can be removed and replaced, unduly extending the conveyor down time required for replacement. In installations where long skirtboards are necessary, the vertical orientation usually used for the aprons may produce excessive friction on the belt, particularly following replacement of the apron or downward adjustment of the apron for wear compensation, with a resulting possibility of damage to the edges of the belts, damage to the conveyor drive, or both.